Telomeres are the nucleoprotein structures found at the ends of linear, eukaryotic chromosomes. They play critical roles in many essential cellular functions, including protection of the ends of the chromosomes from degradation and end-to-end fusion, regulation of the proliferative lifetime of the cell, meiotic segregation, and chromatin silencing. Several conserved protein complexes protect telomeres from recognition by DNA damage machinery, and thus prevent uncontrolled degradation and end-to-end fusions. Our studies will focus on the key protein in telomere end-protection in higher eukaryotes, Pot1. We propose to study the interaction of Pot1 pN and telomeric DNA using solution nuclear magnetic resonance to better understand how end protection occurs. We will first analyze the structure of telomeric DNA free in solution and bound to PotlpN. Next we will analyze the structural changes that occur upon telomeric DNA binding to PotlpN in solution. Finally, we will analyze the dynamic motion of DNA and PotlpN. Taken together, we hope to meld the results of these experiments with the biochemical and X-ray crystallographic studies done on Pot1 to give a complete and clear picture of how end protection is carried out by Pot1.